The growing demand for highly reliable and compact electronic modules requires optimized interconnection and packaging technologies. Emerging materials and cost effective manufacturing concepts, such as using thin film interconnections through a printing technique can offer a high degree of customization and design flexibility. In particular, thin silver structures or thin silver-containing layers have been widely demonstrated as next generation thin film interconnection joints that can be used in next generation electronics and printed electrical circuit boards, including flexible and stretchable substrates.
However, soldering to thin silver structures, such as those produced when using printed silver-containing layers (also referred to as “silver inks”) remains a challenge. For example, standard solders do not wet particularly well to the surface of a printed silver-containing layer, leaving beads of solder on the printed plane rather than forming an ideal solder interconnection joint to the silver-containing layer. This often leads to reduced surface contact areas at the interconnection joint which hinders both the electrical conductance and the mechanical viability of the joint. Further, there is a tendency for the solder to dissolve the printed silver-containing layer, leaving a void instead of making an interconnection joint, thereby causing issues with the silver-substrate adhesion that often leads to delamination.
Currently, soldering to silver has been achieved by high temperature brazing at temperatures ranging from 618° C. to 899° C. where a high silver content filler is used as an intermediate layer that is to be melted in between adjoining surfaces. Another method involves using a specialty, low melting point, high silver content solder in creating the interconnection joint. Regardless, these silver-based interconnection approaches still show poor mechanical strength compared to traditional non-silver solder joints. Therefore, a new approach is needed to satisfy the growing demand for creating reliable interconnection joints that can be used in next generation electronics and printed electrical circuit boards.
In view of the foregoing, improved solderability to silver-containing layers and methods for creating reliable interconnection joints that can be used in next generation electronics and printed electrical circuit boards would be of considerable interest in the art. The present disclosure satisfies the foregoing need and provides related advantages as well.